If there are two all-American traditions that President Trump indulges in most, it’s hamburgers and handshakes. His fast-food fandom is well documented — just ask Wendy’s and McDonald’s — and so are his most famous handshakes — just ask Merkel and Macron.

More than any other president, shaking hands (or in German Chancellor Angela Merkel’s case, not shaking hands) has become a sort of awkward performance art for Trump, or at the very least a spectator sport for the rest of the world. Will POTUS drag the country into another thumb war like the ongoing one between Trump and French President Emmanuel Macron, or will he simply Super Glue his fingers to a fellow head of state’s, as he does with Japanese Prime Minister Shinzo Abe nearly every time they meet?

Trump, famous for his forceful handshake, has become a victim of Emmanuel Macron. See how the French left his mark on poor Donald's hand. Force is strong with this one. pic.twitter.com/eeEhl2BTj0

These are valid questions as Trump continues a European tour that will put him and his hands within striking distance of politicians and rulers alike. One such meeting in particular — a visit with Queen Elizabeth II scheduled for Friday (the same day as massive protests of Trump in London) — will bring the president’s unique way of saying hello into sharp focus. So break out the popcorn and etiquette guides to follow along at home.

According to Laura Akano, a London-based protocol expert who trains children and adults, Trump should try to keep his hands to himself — at least at first.

“It’s really up to her to initiate the greeting,” Akano said of the royal protocol of touching the queen. Basically, just don’t.

“She would extend her hand to you for a handshake, but unless she initiates it, you have your hands by your side,” Akano added. And you should leave it at that. Beyond a light handshake — emphasis on light — there should be no patting, side-hugging, bear hugging, tapping on the shoulder, etc. “It’s just not acceptable,” Akano said.

First lady Michelle Obama famously got into trouble with the protocol police (not a real thing) when she put her hand on Queen Elizabeth’s shoulder during a state visit with President Barack Obama in 2009. It was a no-no, said Akano and other experts, even though the queen returned the gesture; another rule of thumb for proper etiquette devotees is to never point out someone else’s faux pas.

“What etiquette teaches you is to be gracious,” Akano said. So you probably wouldn’t hear the queen say, “Unhand me!” although she might be thinking it. “Itis a big deal and it isn’t,” said Akano, before adding that “the right thing to do is to follow the protocol. Don’t embarrass yourself, that’s the key thing.”

During the Ronald Reagan and George H.W. Bush administrations, Shelby Scarbrough’s job was to help make sure the president didn’t embarrass himself — or the country. As a White House advance team member and later a protocol officer for the State Department, Scarbrough revels in the tiny details and intricacies of other cultures but admitted that there should always be room for human mistakes.

Americans, Scarbrough said, are a friendly bunch by nature and often have to dial it back in formal settings. We’re a bit too touchy-feely and a tad on the aggressive side, culture inclinations that should be restrained when going abroad on official state business. “Sometimes,” she said, “that comes easier to some than others.”

For Scarbrough, Trump’s particular brand of handshake (and back slap and shoulder sweeping) isn’t necessarily a sign of disrespect or scuttling of protocol. If there’s any messaging hidden in the president’s handshake, Scarbrough said, it’s this: I’m a confident businessman. Trump, she added, definitely has a signature style, and it comes straight from the C-suite.